If you ask some people why they would never want to get divorced, they joke that they would not want to have to 'get back down to dating weight', but do married people really give up and get heavier?
It seems to be just the opposite. Marriage is correlated with a positive influence on health and life expectancy. Researchers at the University of Basel and the Max Planck Institute for Human Development, in cooperation with the market research institute GfK, compared the body mass index of married couples with that of singles in nine European countries and show that married couples on average eat better than singles, but that they also weigh significantly more and do less sport.
The researchers compared the relationship between marital status and body mass index, which relates body weight to height. A high body mass index can be a risk factor for chronic illnesses such as diabetes or cardiovascular disease. The researchers drew on representative cross-sectional data from 10,226 respondents in Austria, France, Germany, Italy, the Netherlands, Poland, Russia, Spain, and the United Kingdom.
Beyond their focus on married couples, the researchers conducted additional analyses with cohabiting couples. They also examined possible reasons for weight gain by asking respondents about their eating and exercise behaviors. Findings from all nine countries showed that couples have a higher body mass index than singles – whether men or women. The differences between countries were surprisingly small. According to the World Health Organization, a normal body mass index is between 18.5 and 25. Overweight is defined as an index between 25 and 30, and obesity as above 30.
The average body mass index of the single men in the study was 25.7; that of the married men was 26.3. For women, the average index was 25.1 for singles and 25.6 for married women. Although these differences may seem small, they are meaningful. In an average-height woman of 165 cm or an average-height man of 180 cm, they represent a difference of about 2 kg. Importantly, the effects of socio-economic status, age, and nationality are already taken into account in these results.
“Our findings show how social factors can impact health. In this case, that the institution of marriage and certain changes in behavior within that context are directly related to nutrition and body weight,” says Ralph Hertwig, Director of the Center for Adaptive Rationality at the Max Planck Institute for Human Development in Berlin.
Survey findings on respondents’ eating and exercise behaviors offered possible reasons for this trend. For example, couples reported buying more regional and unprocessed products and less convenience food. Moreover, married men were more likely than single men to buy organic and fair trade food.
The respondents were asked about their eating and exercise behaviors and attitudes in face-to-face interviews. This approach ensures higher data quality: People’s self-reports, for example of their weight, are more realistic if they are asked in person rather than, for example, by telephone.
Citation: Mata, J., Frank, R.,&Hertwig, R. (2015). Higher body mass index, less exercise, but healthier eating in married adults: Nine representative surveys across Europe. Social Science & Medicine. doi:10.1016/j.socscimed.2015.06.001. Top image: University of Vienna